GNRHR and breast cancer: For instance, HAS-methotrexate conjugates were functionalized with GnRH to achieve better incorporation into breast cancer cells, producing a significant rise in methotrexate internalization and its antitumoral activity in GnRH-R-positive breast cancer cells (IC50 of 49.2 vs 5.8 nM for non-targeted nanoparticles and GnRH-targeted nanoparticle respectively) (84).